This design incorporates an efficient drip plate for full distribution of water over the bio-media, an overflow passage, and a larger biological chamber than other brands. A removable post filter sponge allows for an expandable sump to accommodate protein skimmers or other filtration accessories. The rugged 3/16" acrylic construction is durable, easy to install, fits most pre-filter drain lines and is designed for fish tanks up to 60 gallons.